600 V to 1 kV mill feeder cable in the Mahoning Valley

Feeders built for a hard start

Mill drives draw heavily at start, so a feeder to a large motor is not one cable. It is three or four parallel runs of 500 or 750 kcmil per phase, in tray or on rack, with a grounding conductor sized to the overcurrent device. That is why a mill feeder lot is heavy, and why it arrives in sets instead of lengths.

The cable is 600 V to 1 kV, single conductor, with XLPE or EPR insulation under a PVC or CPE jacket. Some of it is armored or in conduit; much of it lies exposed on cable rack above the mill floor, where it has spent years in a hot, dirty, vibrating environment.

A parallel set has to stay a set

Four parallel runs of the same size and construction are one item, not four. They were cut to matched lengths deliberately so the current divides evenly, and a set missing a run is worth less than four loose reels, because nobody wants three of a matched four. Keeping the phase markings legible is half of what makes a set a set.

• 500 kcmil and 750 kcmil single conductor
• Sets of two, three or four runs
• 600 V and 1 kV XLPE or EPR
• Grounding conductor cut to match
• Rack runs with tray clamps still fitted

Cut-offs from motor replacements

When a mill motor is swapped, the feeder may be re-used and re-terminated, cut back a few feet at each end to get past a damaged lug, or replaced outright. The cut-offs are short, five to thirty feet, and they are the hardest part of the lot to value. A twelve-foot piece of 750 kcmil is a heavy object with no application.

Where the cut-offs match a run still in service they are worth keeping separate and labelled. Where they are mixed, they go by weight. Storing them dry matters, because a wet end on a large stranded conductor wicks water along the strands, and that is a slow problem to discover.

The other thing a motor replacement leaves behind is the old termination kit: potheads, stress cones, lugs and heat-shrink in opened boxes. It belongs with the cable rather than in a skip, because a buyer re-terminating the same cable on the same size lug cares about it. It is not weighed, and it is not what makes the load worth collecting.

Condition and the walk on a mill site

Jacket condition is the first check and the easiest to misjudge. A feeder that ran on rack above a furnace has a jacket that is dusty and maybe discolored but still flexible. The same cable near a cooling bed or a scale may be heat-cracked. Bending a sample over a gloved hand tells you which one you are holding.

Access on a Mahoning Valley mill site is controlled, and old mill buildings have low doors, rail crossings and crane bays a trailer cannot enter. Review includes a walk to see how the cable is stored, a sample cut from each set, and a run measured against the plant's drive schedule.